<%@ page contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<%
    if (request.getAttribute("error") != null) { // 登录错误
        out.print(request.getAttribute("error"));
    } else if (request.getSession().getAttribute("Username") != null) { // 登录成功
        out.print("欢迎光临：" + request.getSession().getAttribute("Username"));
    } else {
        out.print("你登录了嘛？"); // 未登录状态
    }
%>